/Engine/Source/Runtime/MovieScene/Public/EntitySystem/MovieSceneInitialValueCache.h
Value must not have been cached previously - doing so will result in a failed assertion
A tuple containing the cached value and its index
[FInitialValueIndex](API\Runtime\MovieScene\EntitySystem\FInitialValueIndex) AddInitialValue ( [UObject](API\Runtime\CoreUObject\UObject\UObject) * BoundObject, const [StorageType](API\Runtime\MovieScene\EntitySystem\TPropertyValueStorage\StorageType) & InValue, uint16 ResolvedPropertyOffset )